Research was carried out on motor function in man in relation to aging. With the use of a patient activity monitor worn on the non-dominant wrist in 43 healthy men for a period of 9 days, it was demonstrated that average motor activity was lower in older individuals, primarily as a result of low activity during daytime hours. Weekend mean activity was significantly different than weekday mean activity only in the younger subjects as a result of young subjects sleeping later on weekends than during the weekday period. The monitor has been shown to be useful in quantifying nocturnal disturbances, such as wandering, in patients with Alzheimer's disease. In patients with Alzheimer's disease, studies of central auditory function using both dichotic and degraded monotic tests showed that performance on the dichotic test was more difficult for the patients, compared to healthy controls. Only dichotic performance was related to measures of cerebral atrophy and glucose metabolism in the temporal lobes. Evoked potential latencies were not different in patients with Alzheimer's disease compared to controls.